CENTRIFUGAL BLOWER WITH NON-UNIFORM BLADE SPACING

• US 20110052385A1
• Filed: 09/02/2009
• Published: 03/03/2011
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Duke, Connor Raymond
• Granted Patent: US 8,398,380 B2
• Time in Patent Office: Days
• US Class Current: 415/203
• CPC Class Codes: F04D 29/281 for fans or blowers
• CPC Class Codes: F04D 29/666 by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
• CPC Class Codes: Y10T 29/49329 Centrifugal blower or fan

Abstract

A centrifugal blower in a cooling system of an electronic device having non-uniform blade spacing with acceptable balance. The non-uniform blade spacing is determined according to specific repeating sinusoidal patterns to obtain acoustic artifacts that are favorable and balance that is similar to that found with equal fan blade spacing. The fan impeller can include a prime number of fan blades to prevent higher harmonic interaction among noise sources. The perceived sound quality from the fan is improved with essentially no effect on the thermal performance of the fan.

Claims

1. A centrifugal blower, comprising:

a motor having a number of pole passes, wherein the number of pole passes is an even number;

a number of impeller blades spaced non-uniformly about a central hub, wherein the number is at least 15, and wherein the number is different from the number of pole passes in the motor; and

wherein an angle of each of the spaces is determined by the blade positions, wherein each of the blade positions corresponds to a unique point on at least two repeating sinusoidal patterns.

2. The centrifugal blower of claim 1, wherein each of the blade positions corresponds to a unique point on four repeating sinusoidal patterns.

3. The centrifugal blower of claim 1, wherein the number of impeller blades is 29 or fewer.

4. The centrifugal blower of claim 3, wherein the number of impeller blades is 17.

5. The centrifugal blower of claim 3, wherein the number of impeller blades is 23.

6. The centrifugal blower of claim 1, wherein each of the blade positions is modified by about 1 percent to about 7 percent compared to evenly spaced impeller blades of an impeller having a same number of impeller blades.

7. An impeller of a centrifugal blower for an electronic device, comprising:

a prime number of impeller blades, wherein the impeller blades are spaced non-uniformly about a central hub and the prime number is at least 17; and

a plurality of spaces between the impeller blades, wherein an angle of each of the spaces is determined by positions of adjacent impeller blades, wherein the positions of each of the impeller blades corresponds to a unique point on at least two repeating sinusoidal patterns.

8. The centrifugal blower of claim 7, wherein the blower comprises at least 17 impeller blades.

9. The centrifugal blower of claim 7, wherein a number of the at least two repeating sinusoidal patterns is even.

10. The centrifugal blower of claim 7, wherein the at least two repeating sinusoidal patterns is four.

11. The centrifugal blower of claim 7, wherein the electronic device is a laptop computer.

12. The centrifugal blower of claim 7, wherein the positions of each of the impeller blades is modified by about 1 percent to about 7 percent compared to evenly spaced impeller blades of an impeller having a same prime number of impeller blades.

13. A method of manufacturing a fan, comprising:

providing a motor having a number of pole passes, wherein the number of pole passes is an even number;

providing a number of impeller blades, wherein the number of impeller blades is at least 15 and wherein the number is different from the number of pole passes in the motor; and

positioning the impeller blades non-uniformly around a central hub such that each blade corresponds to a unique point on at least two repeating sinusoidal patterns.

14. The method of claim 13, wherein the number of impeller blades is 29 or fewer.

15. The method of claim 14, wherein the number of impeller blades is 17.

16. The method of claim 14, wherein the number of impeller blades is 23.

17. The method of claim 13, wherein each blade corresponds to a unique point on at least four repeating sinusoidal patterns.

18. The method of claim 13, wherein positioning comprises modifying each of the blade positions of an impeller having a same number of uniformly spaced impeller blades by about 1 percent to about 7 percent.